The present invention relates to a method of producing alkoxysilanes and precipitated silicas from biogenic silicas. Many plants ranging from diatoms to grasses to trees take soluble silica from water sources and transport it within their systems and deposit it in various forms and places ranging from the shells of diatoms, to the cells of hard woods, to rice hulls and stalks. In the majority of instances the transport systems involved in the biosilification process are not designed to also transport heavy metals. Consequently biogenically deposited silica is relatively free of heavy metal impurities making it a prospective source for high purity silicon containing materials ranging from alkoxysilanes to silica to silicon nitride to silicon carbide to silicon metal. Biogenically produced silica can be defined as being a sustainable resource as for example in the case of any currently grown silica accumulating plant. Their availability in industrially meaningful quantities as byproducts of existing human efforts to produce food and fiber makes this resource commercially important.
For example, according to Non-Patent references 1 to 4, rice hulls are produced in 100 million ton quantities annually as a generally undesirable byproduct of rice milling. They can contain 12-20 wt % silica in an amorphous, high surface area form. There are now multiple studies in the patent and open literature on the recovery of silicon containing materials from rich hulls. Thus, rice hulls and rice hull ash have been used as a starting point to make solar grade silicon, silicon carbide, silicon nitride and also to recover relatively pure silica through dissolution with a base such as alkali or alkaline earth carbonates or hydroxides, tetramethylammonium or choline hydroxide as noted in the following references and references used in these papers which are incorporated herein as prior art.